If you have a valid account, you can try to log in to the submillimeter group UNIX cluster with this applet. Your browser will probably only let you connect to www.submm.caltech.edu with this applet, so there isn't much point in trying to connect to other hosts directly. After you have logged in, you may ssh to other hosts if you wish.
Note that this applet may take a while to load and initialize, so the screen may be blank for a minute or two. After the applet starts running, click on it and then hit return when it prompts for the name of the host to connect to.
setenv DISPLAY hostname:0 xterm &
This should start an "xterm" terminal for you.
Important:Your X-Windows session will not be encrypted. Never type a password in a X-Window. The only place that is safe to type passwords is directly from your original SSH login.
For more information, see Mindbright.